Throat-plate for sewing-machines



J. R. MOFFATT AND R. S. KELSO.

THROAT PLATE FOR SEWING MACHINES.

APPLICATION FILED DEC-21. 1916.

1,358,567. 7 Patented Nov. 9, 1920.

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A Gam a 1. R. MOFFATT AND R. 'S. KELSO. THROAT PLATE FOR SEWINGMACHINES.

APPLICATION FILED 050.21, IBIS.

1,358,567. I Patented Nov. 9, 1920.

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WMQ w r UNITED STATES PATENT OFFICE.

JAMES R. MOFFATT AND RALPH S. KELSO, OF CHICAGO, ILLINOIS, ASSIGNORS"I'O UNION SPECIAL DIAGI-IINE COMPANY, OF CHICAGO, ILLINOIS, ACORPORATION 7 OF ILLINOIS.

THROAT-PLATE FOR SEWING-MAOI-IIMS.

Specification of Letters Patent.

Application filed December 21, 1916. Serial No. 138,223.

States, residing respectively, at Chicago, in

the county of 00k, State of Illinois, have invented certain new anduseful Improvements in Throat-Plates for Sewing-Ma chines, of which thefollowing is a description, reference being had to the accompanyingdrawing and to the figures of reference marked thereon.

The invention relates to new and useful improvements in throat platesfor sewing machines.

An object of the invention is to provide a throat plate which is soconstructed as to give the needle thread loop on the looper, as it ismoved rearwardly by the feed of the material, a partial twist to causethe looper thread which extends through said loop to be bowed laterallyaway from the body of the looper, whereby the looper thread loop will bepositively spread for the entrance of the needle.

A further object of the invention is to provide a throat plate forsewing machines of the above character, which throat plate is formedwith a recess at the side and in front of the needle opening which formsa clearance for that portion of the looper thread extending rearwardlyfrom the forward eye of the looper when said looper is partaking of itsforward movement in advance of the needle, thereby avoiding the frictionbetween said thread and the throat plate which would otherwise occur.

These and other objects will in part be obvious and will in part behereinafter more fully described.

In the drawings which show by way of illustration one embodiment of theinvention Figure l is a top plan view of the throat plate embodying ourimprovements;

Fig. 2 is an enlarged top plan view of a portion of the throat plate;

Fig. 3 is a bottom plan view of that portion of the throat plate shownin Fig. 2;

Fig.4: is a sectional view on the line 4.l of Fig. 2; I

Fig. 5 is a plan view showing in full lines the looper at the forwardend ofgthe stroke and in dotted lines the throat plate having ourimprovements embodied therein;

Fig. 6 is a similar view but showing the looper partly retracted and thelooper thread loop deflected away from the looper by the partial twistgiven to the needle thread loop through the action of our improvedthroat plate thereon;

Fig. 7 is a similar View, but showing the looper having been retractedto a further extent;

Fig. 8 is a similar view, but showing the looper at the rear end of itsstroke;

Fig, 9 is a sectional view through the throat plate, showing the needleand the looper, with the looper at the rear end of its stroke;

Fig. 10 is a similar view, but showing the looper as positioned in Fig.7; and

Fig. 11 is a sectional view through the with the line of feed and entersthe needle thread loop in a direction opposed to the feed, it isdifficult to spread the looper thread loop from the body of the looperso as to separate the strands of the looper thread loop for the entranceof the needle. The present invention is directed to a throat plate whichis constructed so that said throat plate, operating upon the needlethread loop on the looper, will give said needle thread loop a partialtwist in such a direction as to cause said needle loop to deflect thelooper thread extending from the eye of the looper back throughsaidneedle loop to the previous concatenation of the threads away from thebody of the looper. Our improved throat plate is also provided with arecess located relative to the needle opening, so as to form a clearancespace to permit the free spreading of the looperthread loop, and also toprevent the looper thread from reeving across the metal parts of thethroat plate.

Referring to the drawings in detail, our improved throat plate isindicated at 1. Said throat plate is formed with feed slots therein,which are formed so as to receive the feed dogs which move the material.In Fig. 1 of the drawings we have shown a throat plate which is intendedto be used Patented Nov. 9, 1920.

in connection with a single needle machine,

and, therefore, only one needle opening and the construction of thethroat plate adjacentthe same will be described.

Extending rearwardly from the needle 7 opening 3 and ina directionparallel with of the needle opening.

the line of feed, is a slot 5. The direction of the line of feed isindicated by the opening in the throat plate for the feed dog. The feeddog movesback and forth in a direction longitudinally of the openingstherefor. This slot 5 is inclined to theplane .ofwthe work support, asclearly shown in Fig. 4. It is also disposed elative to the needleopening, so as to form a shoulder 6 at the under face of the throatplate, which shoulder extends to one side of thecenter of the needleopening. In other words, the wall 6" of the slot 5 extends from a point7, which is at the right hand side of'the. needle opening as viewed inthe direction of feed, to a point 8 which is at the left hand side Thisslot 5 extends a distance back from the needle opening greater than astitch length, and the shank of the needle thread loopmoves back intothe slot when the material is fed.

The operation of this slot in the throat plate on the needle thread loopwill be made clear from Figs. 5 to 8 of the drawings, wherein the looperis indicated at 9, and the looper thread is indicated at 10. The needlethread is indicated at 11, while the needle is indicated at 12 in Figs.9, 10 and 11 of the drawings.

The needle when it reaches the lower end of its stroke and begins itsupward movement, throws out a loop of thread in the well known manner,and the looper enters the thread loop. In Fig. 5 of the'd'rawings thelooper is indicated at the forward end of its stroke. Tt is still intheneedle thread loop which is indicated at 11. When the looper movesinto the thread loop, it'moves in a direction opposed tothe direction'offeed which is indicated by the arrow in Fig. 5 of the drawings. As thematerial is fed rearwardly by the feed, it will be noted that the lastconcatenation of the threads is really moved'backwardly in the directionof the longitudinal axis of the looper and would tend to cause thelooperthread to lie close to, the body of the looper.

In other words, when the looper moves across the line of the feed, asoccurs in certain types of machines,the feed of the material, which isat ight angles to the longitudinal axis of the looper body, separatesthe looper thread from the body of the looper. In the present case thefeed of itself,however, as abovenoted, is of no as sistance inseparating the looper thread from the bodyof the looper when the loopermoves in a direction parallel with the'line of feed. This backwardmovement of the needle thread loop through the feeding of the materialcarries the shank of the looper .thread loop into the slot 5. Theshoulder (3 is engaged by the right hand strand ofthe needle threadloop, which carriesthe left hand strand first into the slot, as clearlyshown in Fig. 2 of the drawings, and this gives a partial twist to theshankof the needle thread loop which is on the looper.

At this time the looper'thread extends from the eye ofthelooper-througlrthe needle thread loop onthe looper to the previousconcatenation of the'threads. The partial twist given to the needlethread loop on the looper, will cause the looper thread during thebackwardmovement of the looper to be bowed outwardly away from the bodyof the looper, or separated therefrom, as clearly shownin Fig. 6, andthus the looper thread loop is spread so as to permit the, needle toenter between the looper thread and the body of the looper.

As above noted, the shoulder 6 isat one side of the needle opening, andas a result the edge of the wall of the slot 5 directly in rear of thisshoulder is engaged by. the needle thread loop on the looper and thelateral movement of the looper draws the needle loop tightagainst thisedge. This puts the needle thread loop under greater tension and insuresthe positive bowing of the looper thread in the proper direction. itwill be further noted that the looper thread extending from the eye ofthe looper back through the needle thread loop will, at

thread loop, be carried laterally through this lateral shifting of theneedle thread loop,'and this occurs at the time when the half twistingof'the needle thread loop bows the looper thread orseparates it from thebody of the looper. V

The throat plate on the under face there-- of is provided with a recesswhich extends along the side of the needle opening, as inthe point whereit passes through the needle dicated at 13 and in front of the needleThis recess is constructed and disposed so as to provide a clearancespace to permit the free spreading of the looper thread loop and also"to prevent the looper thread from rubbing against the edge of the needleopening, that is, the metal parts of the throat plate, during theforward movement of the looper. There is openin as indicated at 1%.

also a projecting pin on the under faoe of the throat plate which islocated directly in front of the needle opening. This pin plays no partin the positive spreading of the looper thread loop. It does,however,serve as a guard or check to prevent the'loop from closing or the looperthread shifting across the path of the needle until the point of theneedle has passed the looper thread.

It is obvious that minor changes in the details of construction may bemade without departing from the spirit of the invention as set forth inthe appended claims.

Having thus fully described our invention what we claim as new anddesire to secure by Letters Patent is 1. A throat plate for sewingmachines having a needle opening and a slot leading into said needleopening and extending rearwardly therefrom, said slot at the lower faceof the throat plate being disposed at one side of a line extendingdirectly rearwardly from the center of the needle opening so that theshoulder formed between the slot and the needle opening will engage theneedle thread loop on the looper and cause 7 the strands of said needlethread loop to move one after the other into the slot, thus giving apartial twist to the needle thread loop on the loopervfor causing theneedle thread loop to deflect the looper thread away from the body ofthe looper.

f2. throat plate for sewing machines having a needle opening, a slotextending rearwardly from said needle opening and said slot beinginclined to the plane of the throat plate and disposed so that theshoulder formed between the slot and the needle opening at the lowerface of the throat plate will engage the strands of the needle threadloop on the looper and cause said strands to move one after the otherinto the Slot, thus giving a partial twist to the needle thread loop onthe looper for causing said needle thread loop to deflect the looperthread away from the body of the looper.

3. A throat plate for sewing machines having a needle opening and a sloteXtending rearwardly from said needle opening, said slot being inclinedto the plane of the work support and disposed relative to the needleopening so as to give a partial twist to the needle thread loop on thelooper as said needle thread loop is moved into the slot by the feed ofthe material for deflecting the looper thread away from the body ofthelooper, said throat plate having a projecting pin in front of the needleopening adapted to retain the looper thread loop spread after saidlooper thread loop has'been moved away from the body of the looper.

4;. A throat plate for sewing machines having a needle opening and aslot extending rearwardly from the needle opening, said slot beinginclined to the plane of the throat plate, said throat plate having a recess at the side of the needle opening in the under face thereof andalso in advance of the needle opening to form a clearance space for thelooper thread.

In testimony whereof, we aflix our signatures in the presence of twowitnesses.

JAMES R. MOFFATT. RALPH S. KELSO.

Witnesses;

S. Gnonen TATE, F. C. BUTLER.

